gnumeric and gtk-3.20

[Allin Cottrell <cottrell wfu edu>]

I'm running gnumeric 1.12.28 on Arch, which recently updated gtk3 from 
3.18.N to 3.20.2. The effect on gnumeric is not so nice. The row and 
column labels are now totally flat, with no visual indication that 
they function as buttons, and when working with gnumeric there's a lot 
of spew on stderr, with content such as

(gnumeric:5742): Gtk-WARNING **: 
(gtkcssgadget.c:681):gtk_css_gadget_get_preferred_size: runtime check 
failed: (*minimum <= *natural)

(gnumeric:5742): Gtk-WARNING **: Allocating size to GtkLabel 0xf4b930 
without calling gtk_widget_get_preferred_width/height(). How does the 
code know the size to allocate?

I know that the gtk3 update broke many themes, but I'm using the 
standard Adwaita theme so it seems this shouldn't be a theming issue 
(?). Anyway, just wondering if anyone has an idea of what's going on 
here.

--
Allin Cottrell
Department of Economics
Wake Forest University, NC